The Dublin singer-songwriter took full advantage of Heuston Station's piano by performing his song 'Circles' for those passing by.
The piano was first installed in March 2018 but has been missing for the past few weeks due to repairs.
However it is has now been repaired, with Irish Rail using Gavin's mini-concert to announce its comeback.
They said on Twitter: "Our piano is back in Heuston - as Gavin James found out the other day! #musiccantakeyouanywhere."
A video of Gavin's performance went down well with fan's on social media, with one saying: "Wow the acoustics there are so awesome for your voice! Those lucky people!"
Another said: "Wow, what a treat. Would so love to be there."
The 30-year-old will be touring Ireland this year and plays the National Opera House in Wexford on April 12.
He also has 2022 gigs booked in Limerick, Kerry, Derry, Galway, Belfast, Sligo and Mayo.
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